Contractions question

Your throat is strong enough to contain them, so if you're concerned you should be able to learn to keep it closed. It does feel more restrictive though, since there's slight relief associated with being able to blow even a small amount into your mouth. As far as risk goes, some people sometimes blow a few bubbles through their lips, which isn't great, but that's about the extent of it. As you say, it feels 'dangerous' which is why people stay aware of the need to not let water in and so it virtually never happens - a bit like climbing a moderately high rope. There's a disproportionately high awareness of the danger you might let go and fall, which is exactly why everybody clings on for dear life, making it quite a safe activity.

I find that if I relax my upper chest during contractions they are much more pleasant. Perhaps what I am considering upper chest could actually be throat although i do feel like i can do it mouth open without losing air... I will pay more attention next time i am training but it is definitely certain muscles that when tensed make deep contractions feel worse.